Haplophyllum patavinum in its relic habitats on the Euganean Hills (northeastern Italy), 300 years after its discovery (1722–2022)

Italian Botanist 13: 19-26 (2022)

doi: 10.3897/italianbotanist. | 3.83 |74 L \Y Italian Potanlat

Published by Societd Botanica Italiana

https://italianbotanist.pensoft.net

Haplophyllum patavinum in its relic habitats
on the Euganean Hills (northeastern Italy),
300 years after its discovery (1722-2022)

Corrado Tietto!

| Via Trinita 10, 35020 Pernumia, Padova, Italy

Corresponding author: Corrado Tietto (corrado.tietto@gmail.com)

Academic editor: Lorenzo Peruzzi | Received 6 March 2022 | Accepted 7 April 2022 | Published 12 April 2022

Citation: Tietto C (2022) Haplophyllum patavinum in its relic habitats on the Euganean Hills (northeastern Italy),
300 years after its discovery (1722-2022). Italian Botanist 13: 19-26. https://doi-org/10.3897/italianbotanist. 13.83 174

Abstract

This short paper outlines the discovery and current knowledge of the Euganean populations of
Haplophyllum patavinum (L.) G.Don, 300 years after this species was found on the Euganean Hills (NE
Italy) by botanists Pier Antonio Micheli and Giovanni Girolamo Zannichelli.

Keywords

Colli Euganei, conservation, flora, Pier Antonio Micheli

In June 1722 Florence-born Pier Antonio Micheli, during a walking tour on the
Euganean Hills with his Venetian friend Giovanni Girolamo Zannichelli, collected a
species previously unknown to science, which was named Pseudoruta patavina (Micheli
1729; Zannichelli 1730). The time when Micheli and Zannichelli collected this plant
can be inferred from a letter that Antonio Vallisneri (Professor at the University of Padua)
wrote to Giuseppe Giorgi, a Florentine physician, dated 5° June 1722 and stored at
the National Library of Florence, in the Magliabechi collection. In this letter, Vallisneri
reported that Micheli and Zannichelli paid him a visit at home, on their way back from a
walking tour which had started the previous day (4° June 1722) on the Euganean Hills,
heading to Venice in order to collect algae from the lagoon (Targioni-Tozzetti 1858).

Copyright Corrado Tietto. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

20 Corrado Tietto / Italian Botanist 13: 19-26 (2022)

The following year (Tilli 1723), this species was already included in the catalogue
of plants grown at the Botanic Garden of Pisa. In this catalogue, Tilli wrote that
Micheli found this plant “in agris et locis sterilioribus prope Arquatum, in Agro Patavino,
cum Domino Zannichellio detecta fuit” [discovered with Mister Zannichelli among
the tilled and barren lands near Arqua, in the District of Padua]. Later, Micheli
(1729) characterized the new species with a short description, along with a beautiful
iconography, and specifying the place of collection, namely Sassonegro di Arqua,
where this species still grows today. In the library of the Botanical Garden of Padua,
there is also a watercolor painting of the species, contained in a volume iz folio by G.G.
Zannichelli that collects the preparatory coloured drawings for his works: it is the first
color drawing of this species (Tietto and Chiesura Lorenzoni 2000b).

Linnaeus’ (1753) species Ruta patavina is based on Micheli’s works and his
Pseudo-Ruta iconography (Fig. 1) was designated by Townsend (1986) as lectotype
of the name (Peruzzi et al. 2019). Subsequently de Jussieu (1825) split the genus
Ruta into Ruta and Aplophyllum (later corrected by Spach (1849) as Haplophyllum].
Eventually, R. patavina was attributed to Haplophyllum by Don (1831).

Later, this species was found and reported by numerous botanists who visited the
Euganean Hills (Béguinot 1911), since this is the only area in Italy where the plant
grows spontaneously.

Haplophyllum patavinum (L.) G.Don is an Illyrian species (Dolcher 1956-1957;
Townsend 1986; Pignatti et al. 2017), occurring in Italy only in very small areas in the
calcareous sectors around Arqua Petrarca near Padua, then in the mountains of Slove-
nian Karst, Croatia, Bosnia-Herzegovina, Montenegro, north-eastern Albania, Greece,
and south-western Romania.

Accordingly, the Euganean Hills mark the westernmost limit of this species range
(Cappelletti 1956-1957; Dolcher 1956-1957). These Italian populations are seen as
the remains of a wider and continuous past distribution, which became fragmented
due to the alternate climate changes in the post-glacial periods.

Haplophyllum patavinum is a pioneer species in the Euganean Hills. It settles on
loose, superficial, dry and sunny land, where it grows in small scattered but dense groups
on calcareous scree, free from the turf (Fig. 2). Its current habitat is made up of recently
abandoned vineyards and orchards, low-density olive groves, tilled land allowed to rest,
holes dug for reforestation and agricultural works, small recent landslides, road and path
edges and superficially tilled land. These open environments have become increasingly
rare on the Euganean Hills, so that the populations of H. patavinum are slowly becoming
less dense. Once the vegetation canopy closes, these plants become at first small, weak
and devoid of flowers, then within a few years the population disappears. One of the
most interesting peculiarities of this species, whose persistence is notably jeopardised
by the difficulty to reproduce sexually as well as the major modifications of its habitat,
is its capacity to move from areas where its survival has already been compromised to
more suitable areas, located at a relatively short distance.

Comparing recent observations with the data published about 20 years ago (Tietto
and Chiesura Lorenzoni 2000a; Tietto et al. 2001; Masin and Tietto 2005; Rossi di

Haplophyllum patavinum on the Euganean Hills 21

Pseudo-Ritla Tabig°

A wspicivs Laurenti Patarole Cruts Weneti

Figure |. Iconography published in Nova Plantarum Genera (Micheli 1729) and designated as lectotype
of Ruta patavina.

oY) Corrado Tietto / Italian Botanist 13: 19-26 (2022)

cea OZ ; 7A Dr a Ps hoe ‘ 4 coe tA call o" =
Figure 2. Haplophyllum patavinum (L.) G.Don in the Euganean Hills (Padua).

Schio et al. 2005), reveals that the populations of this species seem significantly de-
pleted. A careful monitoring study carried out during the last three years (2019-2021)
detected only nine localities (Fig. 3) out of the ca. 30 previously documented (Fig. 4).
In all these localities small groups of plants can be found, due to vegetation closure
and to invasive breaking up of the calcareous land to obtain space for new vineyards.
Given the peculiar needs of this species, a continuous, weak and superficial disturbance
should be carried out, to guarantee its survival. This species is listed as Vulnerable (VU
[Blab (iii) + 2ab (iii)]) in the Red List of threatened vascular plants in Italy (Orsenigo
et al. 2020). Considering the new data provided here, H. patavinum could qualify for
a higher risk category.

Haplophyllum patavinum on the Euganean Hills 23

Florence

M.Fasolo
301

M.Rusta
396

Mottolone
eo . M.Ventolone
408

M.Piccolo
316

op"
a!
M.Gemola ;
280

M.Calbarina
136

Lake of Arqua

VALLE ™

SAN GIORGIO *

Sassonegro

‘ M.Ricco
Pome ras 329

a e™ EALAONE
= a lk

M.Cecilia
199

Figure 3. Distribution (blue dots) of Haplophyllum patavinum (L.) G.Don in the Euganean Hills (Pad-

ua) as resulting from the surveys carried out in the years 2019-2021.

24 Corrado Tietto / Italian Botanist 13: 19-26 (2022)

M.Rusta
396
Mottolone
M.Ventolone
408
M.Piccolo
316

M.Gemola
280 .

M.Calbarina
136

VALLE ™

SAN GIORGIO * _

Sassonegro
&

oe
; M.Ricco
Comezzara 329
114

.
we TALAONE

Figure 4, Distribution (red dots) of Haplophyllum patavinum (L.) G.Don in the Euganean Hills (Padua)

as resulting from the surveys carried out in the years 1999-2005.

Haplophyllum patavinum on the Euganean Hills 23

Acknowledgements

I am grateful to Lorenzo Peruzzi for his remarks and suggestions. Reviewers are also
acknowledged for their suggestions on the original manuscript.

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